Slideshow template improvement - 'In Progress'

[ChrisBAshton]

The slideshow template has a green tick to say if you've manually examined the contents yet:

But the green tick is immediately applied when you start viewing each batch of images. You don't need to go through to the end, making sure you've checked all screen widths of all batches...

We should have an 'in progress' amber icon which shows that you've started looking at a batch - then it becomes the green tick when you've reached the end of the batch.